Apparatus for drawing an anchor head on a rod or a tight cable

ABSTRACT

An apparatus for drawing an anchor head on a rod or a tight cable, which comprises a single hydraulic piston-cylinder unit of which the cylinder receives the cable therethrough and engages with one end the base plate, and of which the piston rigid with a hollow piston rod having a die secured therein is slidably mounted in a working chamber adapted to be connected to a source of fluid under pressure. An annular distance-piece slidably mounted in said working chamber is adapted to be either interposed between said piston rod and a pair of transverse keys adapted to slide in longitudinal slots formed in said cylinder and disposed between said annular distance-piece and said cable clamping device when said cable is being tensioned, or positioned to bear against the cylinder bottom. A hollow central punch fitted in the bore of said hollow piston rod receives said cable therethrough and engages with one end the socket to be drawn and with the opposite end said pair of transverse keys.

United States Patent [72] Inventor Rene Beghi FOREIGN PATENTS BOiS-COIOmbQS, Frame 772,858 4/1957 Great Britain 254/29 1 P 7 1968 893,567 4/1962 Great Britain 254/29 [22] Fi ed 0v. [45] patented Jan 12:19 v Primary ExamrnerC(l;1arlels) Lalnham [73] Assignee Socrete Des Grands Travaux De Marseille Amman Exammer ene ms y Paris, France Attorneys- Robert E. Burns and Emmanuel J. Lobato [32] Priority Dec. 26,1967 [33] France [31] 133720 ABSTRACT: An apparatus for drawing an anchor head on a rod or a tight cable, which comprises a single hydraulic piston- [54] APPARATUS FOR DRAWING AN ANCHOR HEAD cylinder unit of which the cylinder receives the cable ON A ROD OR A TIGHT CABLE therethrough and engages with one end the base plate, and of 7Chims 3 Drawing Figs which the pistonrigid with a hollow piston rod having a die secured therein IS shdably mounted in a working chamber [52] US. Cl 254/29, ada ted to be connected to a Soul-Ce f fl under ressure P P 52/230 An annular distance-piece slidably mounted in said working [5 l] Int. Cl E04g 21/12 chamber is adapted to be either interposed between said [50] Field of Search 72/391, piston rod and a pair f transverse keys adapted t0 Iid in low 453; 254/29, 29.5; 52/223LCS, 173, 230 gitudinal slots formed in said cylinder and dis osedbetween 'd ld't d'dbll d' sai annu ar lS ance-piece an sal ca e c amping evlce [56] References Cited when said cable is being tensioned, or positioned to bear UNITED STATES PATENTS against the cylinder bottom. A hollow central punch fitted in 2,756,019 7/l956 Von Heidenstam 254/29 the bore of said hollow piston rod receives said vcable 2,844,356 7/ 195 8 Siegfried 254/29 therethrough and engages with one end the socket to be drawn 3,399,865 9/1968 Kelly 254/29 and with the opposite end said pair of transverse keys.

ZC'ZE; 3:) I- 3.9 :i 7 28 [3 l 38 3 A i 4 ,A/n 1s 18 P 4? W 7 W I -33 -1 \xvzzflp 26 34 m l 'SHEET 1 BF 3 PATENTEB JAN 1 21971 APPARATUS FOR DRAWING AN ANCHOR HEAD ON A ROD OR A TIGHT CABLE BACKGROUND OF THE INVENTION ously slipped on the 'cable. In this known apparatus the piston l of the hydraulic unit or actuator for tensioning the cable is rigidly connected to the cable and the cylinder proper reacts against the mass, block or structure in which the cable end is embedded, through the medium of the drawing socket proper and of an intermediate bearing plate. The cylinder of the tensioning unit is fitted in the cylinder of the drawing unit which has one end'rigidly connected to a piston sliding externally ori the tensioning cylinder, and the opposite end rigidly connected to the die in which the drawing socket is engaged.

This apparatus is objectionable in that it requires the use of two separate piston-cylinder units or actuators for performing the tensioning and drawing functions, and furthermore its longitudinal dimensions are relatively important.

It is the essential object of the present invention to avoid the inconveniences set forth hereinabove.

SUMMARY OF THE INVENTION To this end, the apparatus according to the present invention for drawing an anchor head on a rod or a tight cable, which comprises internally a drawing socket through which the cable extends, said drawing socket reacting through the medium of a base plate against the mass, block or structure in which the cable is embedded, and a cable clamping device mounted on the end of the cable, is characterized in that it comprises a single hydraulic piston-cylinder unit of which the cylinder receives the cable therethrough and engages with one end the base plate, and of which the piston rigid with a hollow piston rod having a die'secured therein is slidably mountedin a working chamber adapted to be connected'to a source of fluid under pressure, than an annulardistance-piece slidably mounted in said working chamber is adapted to be. either interposed between said piston rod and a pair of transverse keys adapted to slide'in longitudinal slots formedin said cylinder and disposed betweensaid annular distance-piece and saidv cable clamping device when said cable is being tensioned, or positioned to bear against the cylinder bottom, between this bottom and said transverse keys when drawing the anchor head, and that a hollow central punch fitted in the bore of said hollow piston rod received said cable therethrough and engages with one end the socket to be drawn and with the opposite end said pair of transverse keys.

The cable clamping device comprises a screw-threaded portion on which a nut is engaged and tightened when the cable is tensioned, said nut holding the cable tight by reacting against the cylinder end. i

The apparatus according to this invention is advantageous in that its design is considerably simpler than that of the previously known apparatus, since it comprises only a single pistoncylinder unit or actuator for tensioning the rod or cable and also for drawing the socket on the cable. Besides, its longitudinal dimensions are considerably shorter.

BRIEF DESCRIPTION OF THE DRAWINGS be used.

A specific and preferred form of embodiment of this inven FIG. 3 is a view similar to FIG. 1 but showing the sameapparatus in the condition obtaining after tensioning the cable and before drawing the anchor head thereon.

DESCRIPTION OF THE PREFERRED EMBODIMENT formed with longitudinal holes receiving from end to end the respective cable strands.

The apparatus according to this invention comprises a hydraulic piston-cylinder unit or actuator having an outer cylindrical body or cylinder 4 havingon either side of an annular shoulder 5 a pair of cylindrical chambers 6, 7 in which a return piston 8 and a working piston 9 are slidably fitted, respectively.

These chambers 6 and 7 may be connected to a source of fluid under pressure, respectively through ports 11 and 12 opening into these chambers in the vicinity of the right-hand end of chamber 6 and left-hand end of chamber 7, respectively, as seen in the drawing. In the inoperative condition of the apparatus the return piston 8 and working piston 9 both rigid with a common hollow rod 13 are in their innermost or lefthand position, as shown in FIG. 1.

Mounted inside the hollow piston rod 13 is a die 14 locked against the rod by a nut 15. This die 14 partially surrounds the socket 3 to be drawn and the tubular distance-piece l0 centered on the bearing plate 16 through which the cylinder 4 of the apparatus and the drawing socket 3 bear against the concrete mass 2.

The drawing socket 3 is retained between the tubular distance-piece 10 centered by the base plate 16 and an elongated hollow punch 17 through which extends the cable 1.

The punch 17 has a gradually stepped outer surface, and its outermost portion having the greater diameter is slidably fitted in the bore of rod 13 so that this'rod 13 can move along the punch 17. a

However, this form of embodiment is not compulsory and a cylindrical, frustoconical or otherwise shaped punch l7 may The outermost or right-hand end of punch 17 engages a pair of parallel transverse keys 18, 19 slidably fitted in opposite longitudinal slots 21 and 22 (see FIG. 2) for the upper key 18,

and 23 and 24 for the lower key 19, respectively. The length of these keys 18, 19 is sufficient to enable them to extend across these slots and project from the outer surface of the cylinder 4. V

Before tensioning the cable, these keys 18, 19 are disposed against a self-clamping device 25 mounted on the cable end and having mounted therein tapered keys 26 for clamping the cable strands when the device 25 is moved to the right as seen in FIG. 1. The outer surface of this device 25 is screwthreaded.

A distance-piece 28 comprising a cylindrical central sleeve '29 having welded thereto at either end an outer ring 31, 32 is slidably mounted in chamber 7. Before tensioning the cable, this distance-piece 28 is positioned between theright-hand end of piston 13 and the pair of keys 18, 19 located themselves between the punch 17 and the cable clamping device 25.

An externally threaded nut 33 formed with a central bore 34 receiving the cable 1 therethrough is screwed'in the internally screw-threaded right-hand end portion of cylinder 4. This nut 33 comprises on its inner or left-hand end an extension constituting a cylindrical skirt 35 having slidably mounted thereon an annular piston 36 disposed between this skirt and the bore of cylinder 4. The permissible movement of piston 36 to the left is limited by a stop ring 37 secured to the end of said skirt 35. The chamber 38 in which the piston 36 is movable communicates through an orifice 39 with the source of fluid under pressure (not shown).

"tion fwill bedescribed.

The annular cross-sectional surface area of chamber'38 is greater by at least percent to that of chamber 7.

- Now the operation of the apparatus according to this inven- Assurning the apparatus inits inoperative position shown in FIG/ 1, the cable is firstly tensioned. To this end, fluid under pressure is introduced through port 12 into chamber 7, so that the working piston 9 is urged to the right, as seen in the BIG This thrust is the then transmitted via piston rod 13, distancepie'ce 28 and transverse keys l8 and 19 to the cable selfclamping device 25. Thus, the cable is forced to the right and clamped by the tapered keys 26 so that the cable is moved to the right but bodily with the movable assembly. The drawing socket 3 and the punch l7 arecarriedalong, during this movement to the right, by the die l4 r ig'id with piston rod 13. When the cable I has been tensioned to the desired and proper degree, the clamping device partially projects from the outer or right-hand end of cylinder 4 through the bore 4 of nut 33, and under these conditionsan auxiliary holding nut 42 is screwed on thethreaded portioni27. Thus, when the supply of fluid under pressure to chamber 7 is discontinued the tensioned cable 1 is held in this condition by the auxiliary nut 42 now urged against the nut33. Thus the cable tension is transmitted to the concrete block 2 through the cylinder 4 of the apparatus and, the bearing or base plate 16. I f

With the cable thus tensioneld, fluid under pressure is fed to chamber 6 through port 1 1 The return piston 8 is then urged to the left and restored to'its inoperative position. Thus, the working piston is also returned to its inoperative position as illustrated in FIG. 1; however the distance-piece 28 and the transverse keys 18 and' 19 rerhain in their endmost positions (to the right) where they have been brought during the cable tensioning operation. Then the transverse keys 18 and 19 are removed from the cylinder 4 and the distance-piece 28 is moved to the right-hand end or bottom of cylinder 4, so'that the outer ring 32 of this distance-piece 28 engages to the annular post piston 36. When the distance-piece 28 is in this position the keys l8 and 19 are reinsertedinto their slots as shown in FIG. 3, after the central punch 17 and drawing socket 3 have been restored to their initial positions, Under these conditions, the central punch 17 is held against movement since it bears against the transverse keys l8 and 19 which are themselves held in their slots by the distance-piece 28 bearing against the annular, piston 36. h

Then, fluid under pressure is again supplied to chamber 7. via port 12 in order to move the workingpiston 9 to the right. The resulting movement of die l 4 to the right invoives the drawing of socket 3 which is then held against movement by the central l7.

During the drawing operation the pressures prevailing in chambers 7 and 38, which co'ntrolthe pistons 9 and36'respectively, have the same values. However, as the cross-sectional surface area of annular piston 36 is slightly greater than that of annular piston 9, the force acting on piston'36 is greater than,

that acting on piston 9; however, piston 36 will recedeslightly and gradually as the socket 3 is elongated as a consequence of the drawing force exerted thereon, this elongation being transmitted through punch .17, transverse keys 18 and 1 9 and distance-piece 28. Therefore, piston 36 will cause an antagonistic force to be exerted against punch 17 which is greater than the reaction resulting from the drawingoperation while permitting a gradual backward movement of piston 17 as the die 3 is elongated.

When'the drawing of socket 3 and the fitting of theanchor head have been completed, it"only remains to remove the nut 42 Thus, the cable tension is transferred to the anchor head and through the baseplate 16 to the concrete mass or block 2.

Upon complete removal of the auxiliary nut 42 the apparatus can easily be removed from the cable.

At the beginning of the drawing operation the piston 36 exerts on the socket 3 through the medium of distance-piece 28,

transverse keys l8, l9 and punch 17 a thrust causing this socket 3 to be pressed against the base plate 1Q, whereby any loss of cable tension is avoided when t e auxiliary nut 42 IS scope of the invention since they are given by way of example only; therefore, it would not constitute a departure from the,"

basic principle of this invention to. bring various modifications and variations thereto as will readiiy. occur' to those skilled in the art, within the inventivefield asc rtained in the appended claims; a

lclaim: v Y '1. An apparatus for drawing an anchor head on a rod or tight cable from a drawing socket receiving said cable therethrough, which comprises a base plate through which said socket bears against the structure in which said cable is embedded, a cable clamping device mounted on the cable end, a single hydraulic piston and cylinder unit comprising an elongated cylinder, a cylinder bottom, aworking chamber formed within said cylinder, a working pistonslidably mounted in said working chamber and a hollow piston rod rigid with said working piston, said cylinder receiving said cable therethrough and contacting said base plate with one end, a die secured within said, hollow piston rod, an annular distance-piece slidably rnounted in the working chamber of said cylinder, longitudinal slots formed through said cylinder, a pair of transverse keys adapted to slide in said slots, said annular distance-piece being interposed, during the tensioning of said cable, between said hollow piston rod and said pair of transverse keys, said transverse keys also bearing against said cable clamping device, said annular distance-piece bearing on the other hand against said cylinder bottom, between said bottom and said transverse keys, when drawing the anchor head, and a hollow central punch engaged within said hollow piston rod and receiving said cable therethrough, said hollow central punch contacting with one end said socket to be drawn and with its opposite end said transverse keys.

2. An apparatus as set forth in claim 1, wherein said cable clamping device comprises an externally screw-threaded portion, said apparatus further comprising a nut adapted to engage said screw-threaded portion when said cable is tensioned, in order to hold the cable under tension by reacting against the cylinder end.

3. An apparatus as set forth in claim 1, wherein said cylinder comprises another chamber isolated from said working chamber, and a return piston slidably mounted in said other chamber and rigid with said hollow piston rod.

4. An apparatus as set forth in claim 1 wherein said transverse keys extend completely through said cylinder and their ends project from the outer surface thereof.

5. An apparatus as set forth in claim 1, which further comprises, in the said cylinder bottom, a nut screwed in said cylinder and provided with a central bore of a diameter greater than that of said cable clamping device.

6. An apparatus as set forth in claim 5, wherein said nut screwed in said cylinder bottom has a cylindrical skirtlike extension forming in conjunction with the bore of said cylinder an annular chamber filled with fluid under pressure, an annular bearing piston slidably mounted in said annular chamber, a stop-forming ring secured to said cylindrical skirt and limiting the axial stroke of said annular bearing piston, said annular piston providing a bearing surface for said distance-piece during the drawing of said anchor head.

7. An apparatus as set forth in claim 6, wherein said annular surface area of the working piston is smaller than that of said bearing piston. 

1. An apparatus for drawing an anchor head on a rod or tight cable from a drawing socket receiving said cable therethrough, which comprises a base plate through which said socket bears against the structure in which said cable is embedded, a cable clamping device mounted on the cable end, a single hydraulic piston and cylinder unit comprising an elongated cylinder, a cylinder bottom, a working chamber formed within said cylinder, a working piston slidably mounted in said working chamber and a hollow piston rod rigid with said working piston, said cylinder receiving said cable therethrough and contacting said base plate with one end, a die secured within said hollow piston rod, an annular distance-piece slidably mounted in the working chamber of said cylinder, longitudinal slots formed through said cylinder, a pair of transverse keys adapted to slide in said slots, said annular distance-piece being interposed, during the tensioning of said cable, between said hollow piston rod and said pair of transverse keys, said transverse keys also bearing against said cable clamping device, said annular distance-piece bearing on the other hand against said cylinder bottom, between said bottom and said transverse keys, when drawing the anchor head, and a hollow central punch engaged within said hollow piston rod and receiving said cable therethrough, said hollow central punch contacting with one end said socket to be drawn and with its opposite end said transverse keys.
 2. An apparatus as set forth in claim 1, wherein said cable clamping device comprises an externally screw-threaded portion, said apparatus further comprising a nut adapted to engage said screw-threaded portion when said cable is tensioned, in order to hold the cable under tension by reacting against thE cylinder end.
 3. An apparatus as set forth in claim 1, wherein said cylinder comprises another chamber isolated from said working chamber, and a return piston slidably mounted in said other chamber and rigid with said hollow piston rod.
 4. An apparatus as set forth in claim 1 wherein said transverse keys extend completely through said cylinder and their ends project from the outer surface thereof.
 5. An apparatus as set forth in claim 1, which further comprises, in the said cylinder bottom, a nut screwed in said cylinder and provided with a central bore of a diameter greater than that of said cable clamping device.
 6. An apparatus as set forth in claim 5, wherein said nut screwed in said cylinder bottom has a cylindrical skirtlike extension forming in conjunction with the bore of said cylinder an annular chamber filled with fluid under pressure, an annular bearing piston slidably mounted in said annular chamber, a stop-forming ring secured to said cylindrical skirt and limiting the axial stroke of said annular bearing piston, said annular piston providing a bearing surface for said distance-piece during the drawing of said anchor head.
 7. An apparatus as set forth in claim 6, wherein said annular surface area of the working piston is smaller than that of said bearing piston. 